[205guy]

I think that with low power LED lighting, as well as all rechargeable devices, there is a case for some (not all) 12VDC sockets around the house (and cars/vans/RVs). Actually, I think mobile applications will be first: in an RV, it makes no sense to have a big inverter to take your 12V batteries to 120V AC, just to plug in wall warts to charge to camera, phone, etc.

I have a friend who installed 12V in parts of his house, backed by a solar charged battery system. See my previous comment for some details:

https://news.ycombinator.com/item?id=21109247

Talking to this friend, we discussed the same problem as the OP. In RVs that are wired for battery power, they use wall-mounted cigarette lighter plugs, and you can buy some small appliances that use them. They are ugly and take up too much space, it would be so much better to have a plug of a regular shape and size. Of course it has to be polarized for DC, so something like ( - | ).

There is also the problem of breaking the arc in DC, so one prong needs to be longer and making contact further in so it can't arc outside the plug. Or maybe it needs some internal mechanism such as plastic slot covers that close and break the ark (like child-protected sockets have now). Anyway it definitely needs some research and design, but I think it would be cool to have a new 12VDC standard plug, then people could start designing products that use it to get the whole ecosystem started.